Supplementary bonding involves connecting together the metal parts
of electrical equipment (such as a heated towel rail) and the metal
parts of a non-electrical item (such as a pipe) to prevent a dangerous
voltage between them, if a fault happens.
• Supplementary bonding is often needed in the bathroom to reduce
the risk of electric shock. It can happen as a result of touching the
metal casing of electrical equipment (such as a light fitting or
heater) and at the same time touching a metal non-electrical item
(such as a pipe or radiator) when there is an electrical fault
anywhere in the premises.
• An electrician can carry out supplementary bonding by connecting
together the electrical and non-electrical items referred to above
with a suitable cable (having green and yellow insulation). You
may not normally be able to see existing supplementary bonding.
Supplementary bonding should only be installed by a registeredelectrician.